The invention relates to a bistable magnetic actuator provided with a polarized parallel circuit, wherein between the outer legs of a U-shaped soft-iron yoke a flat permanent magnet is integrated carrying a soft-iron centre leg and applies a permanent-magnetically created magnetic flux to a rocking armature supported on the centre leg, wherein at each outer leg a separately controllable excitation winding provides swiveling pulses for the rocking armature to swivel from one permanent-magnetically self-locking swivel position into the other. In prior art, a similar generic magnetic actuator is described in the utility model specification DE 20 2004 012 292 U1.
In deenergized state bistable, bipolar magnetic actuators can take two stable swivel positions. Frequently, said actuators comprise a parallel connection of two magnetic circuits made of soft-iron components to guide a magnetic flux, one or several electromagnetic excitation windings and at least one permanent magnet that over one or several air gaps generates forces to a magnet armature in the two magnetic circuits, capable to powerlessly lock the magnet armature in both stable positions. Swiveling of the magnet armature is essentially determined by the interaction between the flux generated by the excitation windings and the permanent-magnetic fluxes through the soft-magnetic parallel circuits.
According to the aforementioned generic DE 20 2004 012 292, prior art knows a rocking armature of a flat design antifriction mounted at the centre leg to actuate a charge changing valve of an internal combustion engine. A permanent magnet integrated in the centre leg creates a holding force holding the rocking armature in one of the two swivel positions while demanding no flow of current. By alternately energizing both excitation windings at changing polarity the rocking armature alternately swivels by that the respective wing of the rocking armature assigned to the energized excitation winding is attracted due to the addition of the permanent-magnetically created secondary flux over the open armature air gap and the unidirectional, in each case, electromagnetic flux over the open armature air gap. Swiveling over occurs against the holding force of the permanent-magnetically created flux through the dead parallel circuit that has established over the closed armature air gap having locked the rocking armature in its position until then.
Many known magnetic actuators for electromagnetic drive systems with a reversible excitation winding or two separately controllable excitation windings are based on the described principle such as to DE 6751 327 DE 1 938 723 U1, DE 43 14 715 A1, DE 696 03 026 T2, EP 0 197 391 B2. Always the excitation winding in that parallel circuit is energized to the side of which the rocking armature is intended to swivel, with the electromagnetic flux directed equal-sense to the permanent-magnetically created secondary flux. In each case, however, the holding force the permanent-magnetically created flux exerts on the attracted armature wing must be overcome, which requires a significant energetic effort.
Further, from DE 33 23 481 A1, for example, polarized bistable relays with a one-mesh magnetic circuit and a rotatable H-armature pull equipment provided with a permanent magnet are known where the H-armature pull equipment is swivelable into its two switching positions by the magnetic field of an excitation winding To switch the relay the polarity of the magnetic field is reversed by applying a voltage pulse in each case so that the H-armature pull equipment swivels into the respective other switching position. But also here the electromagnetic flux is created on the H-armature pull equipment to be swiveled over.
The objective of this invention is to provide an energy-efficient bistable magnetic actuator having a simple low-weight, low-volume design and a high switching power density that is particularly suitable for bistable relays of high switching capacity.